Tim & Moby Why we Eat

A balanced diet requires the correct food groups in the correct amounts.

These include:

• Carbohydrates• Fats• Proteins• Vitamins• Minerals• Fibre• Water

simple carbohydrates: sugars

e.g. Glucose in

Lactose in milk

Use: energy release

complex carbohydrates:

cellulose, in plant cell walls e.g. fruitUse: Provides support

glycogen, found in animal liver & muscle cells

starch, found in plant cells e.g. bread, pasta, rice

Use: energy storage

made from fatty acids and glycerol

animal fats are solid e.g. butterplant fats are liquids e.g. olive oilUse: insulation, protection,

energy storage

made from amino acidsAnimal protein e.g. eggs,

meat, fishPlant protein e.g. nuts,

pulses, QuornUse: growth and repair

Needed in only very small amounts and are

important in maintaining our general health

• Found in fresh vegetables and citrus fruit

• It is needed to maintain blood vessels, and for development of teeth and gums

• A deficiency of vitamin C leads to scurvy (sore gums and bleeding around bones and from the intestine)

• Found in fish liver oil, liver, milk, eggs• The skin can also make vitamin D when

exposed to sunlight• It is needed to regulate the use of calcium

and phosphorus for making bones and teeth• A deficiency of vitamin D leads to rickets

(soft bones that bend and dental decay)

Also needed in very small amounts

• Found in dairy products• It is needed for making bones and

teeth

• A deficiency leads to poor development of bones and teeth

• Found in red meat• It is needed for making haemoglobin

in red blood cells• A deficiency of iron causes anaemia;

anaemic people are very tired. This is because haemoglobin allows RBCs to carry oxygen which is needed for respiration to release energy.

Read page 32 and make notes on

For both you need to write• What it is used for• Where we get it• What happens if it is deficient

Tim & Moby Healthy Eating

Starvation

• Starvation occurs when a person does not get enough food to eat.

• The body is using more energy than the diet is supplying.

Malnutrition

The correct quantity of food is eaten, but it

may consist of only one food type, or a poor balance.

Kwashiorkor results from a diet lacking

enough protein. It results in swollen stomach and is common in countries

where the diet consists mainly rice or maize

Negative:No change from yellow/brown

Positive:Blue/black

Negative:No change from blue

Positive:Green, yellow/orange, brick red

Negative:No change from clear

Positive:Cloudy suspension

Food Tests

Worksheet

Cluedo activity

The fewer drops of juice added , the

more vitamin C is present in the liquid.

•The variable changed was the treatment of the Fruit Juice•The same volume of DCPIP was used in each experiment•The same type of juice was used

•Discuss the reliability of the class results•Results that are far away from the others are called anomalous results •Do you have any anomalies?

•It would have been more accurate to use a measuring cylinder to measure the 1cm3 DCPIP. •The syringe did not measure exactly 1cm3, so some experiments had more or less DCPIP.

•It was not possible to control the size of the drops of fruit juice using a dropper.•It would have been more valid to use a burette and measure the volume of fruit juice needed to change the DCPIP from blue to clear.

• Use the trial controlled assess material?

Comparing the energy content of different foods (WS)

BT in clampThermometer

Mounted needle

Boiling tube

25cm3 water

Energy needed per day by different people in different situations

3 main factors affect our energy requirements, and therefore how much and what we need to eat

Pregnant women need extra nutrients for the developing baby:

• calcium for the growth of bones

• iron for the production of red blood cells

Nursing or breastfeeding mothers need extra

• Protein & fluid to make milk

The body mass index is a measure of whether

someone is the correct weight for their height.

BMI = weight

height 2

Weight is measured in kg

Height is measured in metres

Using BMI valuesBMI value Description

Under 18.5 Underweight

18.5 – 24.9 Normal

25 – 29.9 Overweight

30+ Obese

This graph allows you to compare the BMI of a range of boys of the same age.

Percentiles are used to indicate the range of values associated with being •underweight, less than 5%•ok, 5-85%•overweight, 85-95%•and obese, over 95%.

Percentage increase in BMI can be calculated by finding the difference between the initial and final BMI. Divide this by the initial BMI and multiply by 100.

Percentage change in BMI = CHANGE IN BMI X 100 initial BMI

e.g.A 10 year old boy on the 85th percentile has a BMI of 19.5At 20 years old on the 85th percentile he has a BMI of 27.0

Change in BMI = 27.0 – 19.5 = 7.5

% change in BMI = 7.5 X 100 = 38.5%19.5

The basal metabolic rate is a measure of the minimum

energy use.It is found when a person is inactive, resting in a reclining

positionThe person must not be stressed

due to hunger, but must have digested their last meal.

BMR calculatorTo calculate your BMR you need to know:

HeightWeight

Agegender

Using BMr values

Use the HARRIS BENEDICT EQUATIONto calculate how much energy you need,

in calories

From the table decide the activity factor.Multiply the BMR by the activity factor.

This gives the number of calories youneed to eat to stay at your current weight.

A 15 year old girls is 1.6m tall and 57Kg.

Her BMR (from calculator) is 1419.7.

She is quite active, playing netball and hockey for the school teams, so she

practises every day.

Her activity factor is 1.725 (very active).To find the energy she needs multiply BMR

by activity factor.

1419.7 x 1.725 = 2229 Calories = 10.25 Kj

Activity factor Category

1.2 Minimal exercise

1.375 Lightly active

1.55 Moderately active

1.725 Very active

1.9 Extremely active

The factors which affect health and cause these diseases can be divided into 3 groups:

• Dietary e.g eating too much saturated fat, sugar or salt and eating too little fruit and vegetables

• Environmental e.g. stress

• Hereditary the genes you inherit from your parents can make you more susceptible to certain diseases such as heart disease

It is possible to control diet and environmental factors, and so reduce the chance of getting these diseases.

Whilst it is not possible to control the genes you inherit, by controlling the effects of diet and environmental factors you are reducing the chance of getting these diseases to a minimum.

The number of people with obesity has doubled over the past 20 years to 20% of the population.

The NHS is paying more to treat people for obesity and for the medical conditions associated with obesity such as type 2 diabetes and heart disease.

Read the following articles

• Obesity Tsunami

• Talking scales to combat obesity

• In pairs produce a slogan, no longer than 10 words, which could be used in the campaign to fight against obesity.